ETYM Late Lat. collateralis; col- + lateralis lateral. Related to Lateral.
1. Accompaniment to something else.
2. Descended from a common ancestor but through different lines; SYN. indirect, oblique.
3. Serving to support or corroborate; SYN. confirmative, confirming, confirmatory, corroborative, corroboratory, substantiating, substantiative, validating, validatory, verificatory, verifying.
4. Situated or running side by side.
5. Derived from same main stock but subsidiary; secondary.
6. Security available in return for a loan. Usually stocks, shares, property, or life insurance policies will be accepted as collateral.

A security pledged for the repayment of a loan.
Real estate, equipment, inventory, and even accounts receivable pledged as security when a company borrows money from a lending institution. (The resulting loan is known as a secured loan.)